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Squash (Cucurbita spp.)-Gummy Stem Blight (Black Rot) Cause A fungus, Didymella bryoniae (asexual: Phoma cucurbitacearum), which overwinters on crop refuse and attacks numerous other cucurbits. The fungus will not survive in soil without cucurbit refuse o ...

Squash (Cucurbita spp.)-Pollination Failure Cause Lack of pollen or inactive pollen. Symptoms Fruit fail to enlarge and can turn brown from the blossom end. Blossoms fall off. Often, part of the fruit develops normally but the rest does not, resulting in ...

Squash (Cucurbita spp.)-Powdery Mildew Cause The fungi, Golovinomyces cucurbitacearum (formerly G. cichoracearum and Erysiphe cichoracearum), Podosphaera xanthii (formerly P. fuliginea and Sphaerotheca fuliginea), and Leveillula taurica (anamorph = Oidiop ...

Squash (Cucurbita spp.)-Pythium Root Rot See: Squash (Cucurbita spp.)- Damping-off Cause Several Pythium spp. have been described. P. aphanidermatum causes a sudden wilt. Cool, wet soils favor these fungus-like microorganisms. Symptoms Mature plants wilt ...

Squash (Cucurbita spp.)-Scab (Gummosis) Cause The fungus, Cladosporium cucumerinum, which overwinters in cucurbit debris in soil, in greenhouse cracks and corners, and on seed. It can infect and severely injure fruit at all growth stages, particularly whe ...

Squash (Cucurbita spp.)-Sclerotinia Stem Rot Cause The fungus, Sclerotinia sclerotiorum, has been observed frequently in Oregon, particularly on zucchini and kubocha squash. This fungus overwinters in soil as sclerotia or on old infected plant material. T ...

Squash (Cucurbita spp.)-Septoria Leaf Spot Cause The fungus, Septoria cucurbitacearum, can infect leaves and fruit and many cucurbits. It was found in zucchini fields in the Willamette Valley during 2004. The fungus survives on host debris for more than a ...

Squash (Cucurbita spp.)-Storage Rots By Cynthia M. Ocamb and Hannah Rivedal Cause The common storage diseases of squash are Alternaria fruit rot (Alternaria cucumerina), black rot (Didymella bryoniae), Fusarium rot (many Fusarium spp. including F. solani ...

Squash (Cucurbita spp.)-Verticillium Wilt See: Watermelon (Citrullus sp.)- Verticillium Wilt ...

Squash (Cucurbita spp.)-Virus Diseases See: Squash (Cucurbita spp.)- Curly Top Cause The three most common virus diseases in Oregon are zucchini yellows caused by the Zucchini yellows mosaic virus (ZYMV), watermelon mosaic caused by Watermelon mosaic viru ...